The present invention relates to an inductive charger coupling for charging batteries of electric vehicles.
Battery-powered electric vehicles use a charger for charging their batteries. In recent years, chargers tend to have high voltage to lower the energy loss of the wiring. Electric vehicles are often used in rainy and dusty environments, and it is desirable that chargers that endure such environment be safe. In inductive chargers, a battery is charged from an external power source using electromagnetic induction. Inductive chargers ensure charging under rainy and dusty environment since they use electromagnetic induction. Accordingly, inductive chargers are suitable for electric vehicles.
Inductive chargers have a coupling including a charging paddle for supplying power and a receptacle for receiving power. The charging paddle is connected to an external power source. The receptacle is connected to a battery of an electric vehicle. Battery charging is performed by electromagnetic induction with the paddle and the receptacle close to one another, but not contacting.
For example, Japanese Unexamined Publication No. 7-39077 describes an inductive charger having a communication device using light for communication between a charging side and a charged side. The charged side has a transmitter and the charging side has a receiver. The communication device sends information such as a signal indicating completion of charging from the charged side to the charging side. The supply of electric current from the external power source is stopped based on the information. This prevents useless supply of current from the external power supply after the battery is completely charged. Accordingly, the external power supply does not waste power.
Generally, the reliability of the optical communication device is degraded by sunlight and dust. Light and dust do not affect the reliability of radio wave communication. However, radio waves lack directivity and are transmitted in a wide range, and this may cause jamming. For example, when charging at the charging station, there might be interference from other inductive chargers, or the radio waves from the communication device of the charger may interfere with televisions or FM radios.
To avoid jamming, it is necessary to use high frequency radio waves. However, to receive a high frequency radio waves, it is necessary to connect the communication circuit to an antenna using a coaxial cable. In this case, the communication device is complex and large, and so is the charger. Further, the receptacle needs a cover for sealing out water and dust. This further enlarges the size of the receptacle.
In electric vehicles, installed equipment should be compact and lightweight. Therefore, a large-size receptacle on any part of the electric vehicle results in a poor design.